\section{数字对齐}

% P{-m.n}
\begin{tabular}{P{2.5}P{-2.5}}
\toprule
\multicolumn{1}{c}{数学常数} &
\multicolumn{1}{c}{物理常数} \\
\midrule
3.14159 & 2.99792 \\
27.18281 & -17.58819\\
\bottomrule
\end{tabular}
